Engine seems to run fine while driving, but when coming to a stop, or when idling, will sometimes just quit. Can advance RPM slightly with accelerator to keep going. No check engine light, and no codes that can be read with OBDII or by cycling the ignition key. Tried cleaning IAC, no help. Tried replacing IAC, no help. Tried Valvoline water remover in fuel tank, no help. Idle RPM is 680-705. OBDII checks show spark advance varying between 3* & 22* degrees with constant idle RPM (can't be normal) and advances to 45* with RPM increase; comparison with Chrysler Town & Country showed spark advance very stable with similar RPM advance. Idle throttle position is stable at 11.3%. MAP is 10.3 solid at idle. Inlet Air Temp is 163* at idle. Tried ECM reset by disconnecting battery overnight, no help. Am considering sending ECM to Cardon for repair/rebuild. Also considering trip to local Dodge dealer for further diagnosis. Has anyone had similar issues that were solved with an ECM repair/replacement? Other ideas??? Thanks for any assistance, and Happy New Year!

 

I think your tps reading is too low , for comparison mine is at 13.7 and idles around between 700-800 rpm with occasional dips to the high 680-690 rpms , and your map reading doesnt look right , my scan tool reads in kpa and shows my map reading at 99 with engine off and at 43 with engine running . I dont think your PCM is the problem at the moment .

 

You may want to have your battery load tested and your alternator checked. A weak or dying cell in a battery will not let the battery come up to full charge and these Magnum engines want to see a fully charged battery or they do not like to idle. Just a suggestion.

 

Thanks for the input. Will investigate further and advise.

 

Thanks for the input. Will investigate further and advise findings when complete.

 

Update: Took truck to Dodge dealer today. On the way over the engine stumbled a few times at highway speed and noted that the speedometer instantly dropped about 10MPH and then went back to correct speed. Tech initially suspected cam or crank sensor but when connected to PCM with diagnostics noted "Starts Since Clear" reading 1. Tech says this is an indication that the PCM is losing power due to an internal fault. All other indications on diagnostics for sensor inputs to PCM were reading correctely. In process now to order an exchange PCM from Rock Auto. Tech's confidence is high that PCM will resolve issues. Will update again after replacement PCM is installed.

BTW, 43 kpa = 12.7 in/Hg. MAP on my truck reads 10.3 in/Hg at idle.

 

Have you had the battery load tested and the alternator output checked yet? Don't order that new PCM until you do. You may save a lot of $$$.

 

Ok, I'll do that first......cranking is not a problem and you'd think with a dead cell or low battery capacity this would cause symptoms other than the ECM going bonkers. But fully agree that this would be greatly preferred to buying an ECM or having mine R&R'd!!! Thanks for your insistence that I have this checked first!

Any recommendations for the best place to have the ECM R&R'd (repaired and reprogrammed)? Web search has found dodgecomputers.com, a division of autocomputerexchange.com, and ecmdepot.com as the most likely service providers.

 

A battery with 11 volts will still start your engine just fine but these trucks want to see at least 12-12.5 volts or the electronics start doing some stupid things and you'll have little gremlins running around every where!

 

Bought a refurbished PCM from DodgeAutoComputers.com. Installed replacement and truck ran fine for 30 miles then wouldn't start at all. Reinstalled original PCM and engine started fine but idle problems returned. Contacted DodgeAutoComputers.com and advised them the PCM they sent was defective, so they agreed to send a replacement. Installed second replacement and truck is back to normal! DodgeAutoComputers.com was significantly less expensive than RockAuto.com and other vendors compared online, and their handling of the in-warranty failure was commendable. My cost was $199 and they even paid the return freight.